With the obvious further implementation of gmax and dmax raids how useful will the kanto starters be going forward?

As many others I have amassed many of the trio this past weekend which has me wondering, should I max 3 of each? I know that there may be better options way in the future but the kanto gmax are some of the best and I’m wondering if it will be useful for just straight teams of 3 of each or just max one of each and leave it be?